The present invention relates to an interior finish surface material for automobiles, and more particularly to a surface material for interior equipments of automobiles comprising built-up layers having a stretchability sufficient for heat molding, a low shrinkability and a good retainability of embossed patterns.
In recent years, artificial leathers or synthetic resin coated fabrics have been widely used for interior finish of automobiles as a leather substitute. These synthetic surface materials have an appearance and a feeling of touch which are similar to natural leathers. Various kinds of the synthetic surface materials such as vinyl chloride type, urethane type and other resin types are known, and the vinyl chloride resin surface materials are the most popular.
As the structures of these synthetic surface materials, there are known, for example, a two layer structure consisting of a surface layer (skin layer) and a base layer as a backing material for the surface layer, a three layer structure consisting of a surface layer, a foam layer and a base layer as a backing, and a two layer structure consisting of a surface layer and a foam layer. The three layer structure consisting of the surface, foam and base layers is the most popular among them.
The surface layer is used for the purpose of providing appearance and feeling of touch resembling natural leathers, and the foam layer is used for providing feeling of touch like natural leathers. The base layer is for keeping a shape and/or for improving the feeling of touch, and plastic sheets such as vinyl chloride resin sheets and fabrics of various kinds of synthetic and natural fibers have been generally used as the base layer.
In case of using these surface materials as the automobile interior finish surface materials, they are stuck to interior materials or equipments of automobiles such as trim, instrument panel and seat. The surface materials may be previously formed into the same shape as the interior equipments or parts of automobiles in order to raise the productivity in assembling, and a heat molding such as vacuum molding is a popular molding method for this purpose.
In case of conducting the heat molding such as vacuum molding, it is necessary that surface materials sufficiently stretch at a molding temperature without breaking, and the shrinkability of molded surface materials after releasing from a mold is small. It is also important that embossed patterns do not disappear by heat and stretching in the heat molding, namely the retainability of embossed pattern is good.
With respect to the required stretchability at a molding temperature, it varies depending on the shapes of automobile interior equipments, but in some cases, a stretchability of 100% or more is required. With respect to the shrinkability after molding, a shrinkability of about 20/1000 or less is generally desirable from the viewpoint of matching or engagement with automobile interior equipments. A usual manner for decreasing the shrinkability is incorporation of inorganic fillers such as talc, but the incorporation of inorganic fillers has the defect that the stretchability of the obtained surface materials is decreased.
Plasticized polyvinyl chloride sheets composed of vinyl chloride resins, plasticizers and stabilizers are generally used as the surface layer and as the plastic sheet base layer. In case of usual plasticized polyvinyl chloride sheets, the stretchability at a molding temperature does not reach 100%, and in particular, those containing inorganic fillers show a smaller stretchability.
It is an object of the present invention to eliminate defects of known interior finish surface materials for automobiles.
A further object of the present invention is to provide an automobile interior finish surface material having a sufficient stretchability required in heat molding, a low shrinkability after molding and a good retainability of embossed pattern.
These and other objects of the present invention will become apparent from the description hereinafter.